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/*
Licensed Materials - Property of IBM
DB2 Storage Engine Enablement
Copyright IBM Corporation 2007,2008
All rights reserved
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
(a) Redistributions of source code must retain this list of conditions, the
copyright notice in section {d} below, and the disclaimer following this
list of conditions.
(b) Redistributions in binary form must reproduce this list of conditions, the
copyright notice in section (d) below, and the disclaimer following this
list of conditions, in the documentation and/or other materials provided
with the distribution.
(c) The name of IBM may not be used to endorse or promote products derived from
this software without specific prior written permission.
(d) The text of the required copyright notice is:
Licensed Materials - Property of IBM
DB2 Storage Engine Enablement
Copyright IBM Corporation 2007,2008
All rights reserved
THIS SOFTWARE IS PROVIDED BY IBM CORPORATION "AS IS" AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
SHALL IBM CORPORATION BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
OF SUCH DAMAGE.
*/
#include "ha_ibmdb2i.h"
/* Helper function for records_in_range.
Input: Bitmap of used key parts.
Output: Number of used key parts. */
static int getKeyCntFromMap(key_part_map keypart_map)
{
int cnt = 0;
while (keypart_map)
{
keypart_map = keypart_map >> 1;
cnt++;
}
return (cnt);
}
/**
@brief
Given a starting key and an ending key, estimate the number of rows that
will exist between the two keys.
INPUT
inx Index to use
min_key Min key. Is NULL if no min range
max_key Max key. Is NULL if no max range
NOTES
min_key.flag can have one of the following values:
HA_READ_KEY_EXACT Include the key in the range
HA_READ_AFTER_KEY Don't include key in range
max_key.flag can have one of the following values:
HA_READ_BEFORE_KEY Don't include key in range
HA_READ_AFTER_KEY Include all 'end_key' values in the range
RETURN
HA_POS_ERROR Error or the storage engine cannot estimate the number of rows
1 There are no matching keys in the given range
n > 0 There are approximately n rows in the range
*/
ha_rows ha_ibmdb2i::records_in_range(uint inx,
key_range *min_key,
key_range *max_key)
{
DBUG_ENTER("ha_ibmdb2i::records_in_range");
int rc = 0; // Return code
ha_rows rows = 0; // Row count returned to caller of this method
uint32 spcLen; // Length of space passed to DB2
uint32 keyCnt; // Number of fields in the key composite
uint32 literalCnt = 0; // Number of literals
uint32 boundsOff; // Offset from beginning of space to range bounds
uint32 litDefOff; // Offset from beginning of space to literal definitions
uint32 literalsOff; // Offset from beginning of space to literal values
uint32 cutoff = 0; // Early exit cutoff (currently not used)
uint64 recCnt; // Row count from DB2
uint16 rtnCode; // Return code from DB2
Bounds* boundsPtr; // Pointer to a pair of range bounds
// Bound* boundPtr; // Pointer to a single (high or low) range bound
LitDef* litDefPtr; // Pointer to a literal definition
char* literalsPtr; // Pointer to the start of all literal values
char* literalPtr; // Pointer to the start of this literal value
char* tempPtr; // Temporary pointer
// char* tempMinPtr; // Temporary pointer into min_key
int minKeyCnt = 0; // Number of fields in the min_key composite
int maxKeyCnt = 0; // Number of fields in the max_key composite
size_t tempLen = 0; // Temporary length
uint16 DB2FieldWidth = 0; // DB2 field width
uint32 workFieldLen = 0; // Length of workarea needed for CCSID conversions
bool overrideInclusion; // Indicator for inclusion/exclusion
char* endOfLiteralPtr; // Pointer to the end of this literal
// char* endOfMinPtr; // Pointer to end of min_key
uint16 endByte = 0; // End byte of char or graphic literal (padding not included)
bool reuseLiteral; // Indicator that hi and lo bounds use same literal
char* minPtr = NULL; // Work pointer for traversing min_key
char* maxPtr = NULL; // Work pointer for traversing max_key
/*
Handle the special case of 'x < null' anywhere in the key range. There are
no values less than null, but return 1 so that MySQL does not assume
the empty set for the query.
*/
if (min_key != NULL && max_key != NULL &&
min_key->flag == HA_READ_AFTER_KEY && max_key->flag == HA_READ_BEFORE_KEY &&
min_key->length == max_key->length &&
(memcmp((uchar*)min_key->key,(uchar*)max_key->key,min_key->length)==0))
{
DBUG_PRINT("ha_ibmdb2i::records_in_range",("Estimate 1 row for key %d; special case: < null", inx));
DBUG_RETURN((ha_rows) 1 );
}
/*
Determine the number of fields in the key composite.
*/
if (min_key)
{
minKeyCnt = getKeyCntFromMap(min_key->keypart_map);
minPtr = (char*)min_key->key;
}
if (max_key)
{
maxKeyCnt = getKeyCntFromMap(max_key->keypart_map);
maxPtr = (char*)max_key->key;
}
keyCnt = maxKeyCnt >= minKeyCnt ? maxKeyCnt : minKeyCnt;
/*
Handle the special case where MySQL does not pass either a min or max
key range. In this case, set the key count to 1 (knowing that there
is at least one key field) to flow through and create one bounds structure.
When both the min and max key ranges are nil, the bounds structure will
specify positive and negative infinity and DB2 will estimate the total
number of rows. */
if (keyCnt == 0)
keyCnt = 1;
/*
Allocate the space needed to pass range information to DB2. The
space must be large enough to store the following:
- one pair of bounds (high and low) per field in the key composite
- one literal definition per literal value
- the literal values
- work area for literal CCSID conversions
Since we don't know yet how many of these structures are needed,
allocate enough space for the maximum that we will possibly need.
The workarea for the literal conversion must be big enough to hold the
largest of the DB2 key fields.
*/
KEY& curKey = table->key_info[inx];
for (int i = 0; i < (int) keyCnt; i++)
{
DB2FieldWidth =
db2Table->db2Field(curKey.key_part[i].field->field_index).getByteLengthInRecord();
if (DB2FieldWidth > workFieldLen)
workFieldLen = DB2FieldWidth; // Get length of largest DB2 field
tempLen = tempLen + DB2FieldWidth; // Tally the DB2 field lengths
}
spcLen = (sizeof(Bounds)*keyCnt) + (sizeof(LitDef)*keyCnt*2) + (tempLen*2) + workFieldLen;
ValidatedPointer<char> spcPtr(spcLen); // Pointer to space passed to DB2
memset(spcPtr, 0, spcLen); // Clear the allocated space
/*
Set addressability to the various sections of the DB2 interface space.
*/
boundsOff = 0; // Range bounds are at the start of the space
litDefOff = sizeof(Bounds) * keyCnt; // Literal defs follow all the range bounds
literalsOff = litDefOff + (sizeof(LitDef) * keyCnt * 2); // Literal values are last
boundsPtr = (Bounds_t*)(void*)spcPtr; // Address first bounds structure
tempPtr = (char*)((char*)spcPtr + litDefOff);
litDefPtr = (LitDef_t*)tempPtr; // Address first literal definition
tempPtr = (char*)((char*)spcPtr + literalsOff);
literalsPtr = (char*)tempPtr; // Address start of literal values
literalPtr = literalsPtr; // Address first literal value
/*
For each key part, build the low (min) and high (max) DB2 range bounds.
If literals are specified in the MySQL range, build DB2 literal
definitions and store the literal values for access by DB2.
If no value is specified for a key part, assume infinity. Negative
infinity will cause processing to start at the first index entry.
Positive infinity will cause processing to end at the last index entry.
When infinity is specified in a bound, inclusion/exclusion and position
are ignored, and there is no literal definition or literal value for
the bound.
If the keypart value is null, the null indicator is set in the range
bound and the other fields in the bound are ignored. When the bound is
null, only index entries with the null value will be included in the
estimate. If one bound is null, both bounds must be null. When the bound
is not null, the data offset and length must be set, and the literal
value stored for access by DB2.
*/
for (int partsInUse = 0; partsInUse < (int) keyCnt; ++partsInUse)
{
Field *field= curKey.key_part[partsInUse].field;
overrideInclusion = false;
reuseLiteral = false;
endOfLiteralPtr = NULL;
/*
Build the low bound for the key range.
*/
if ((partsInUse + 1) > minKeyCnt) // if no min_key info for this part
boundsPtr->LoBound.Infinity[0] = QMY_NEG_INFINITY; // select...where 3 between x and y
else
{
if ((curKey.key_part[partsInUse].null_bit) && minPtr[0])
{ // min_key is null
if (max_key == NULL ||
((partsInUse + 1) > maxKeyCnt)) // select...where x='ab' and y=null and z != 'c'
boundsPtr->LoBound.Infinity[0] = QMY_NEG_INFINITY; // select...where x not null or
// select...where x > null
else // max_key is not null
{
if (min_key->flag == HA_READ_KEY_EXACT)
boundsPtr->LoBound.IsNull[0] = QMY_YES; // select...where x is null
else
{
if (maxPtr[0])
boundsPtr->LoBound.IsNull[0] = QMY_YES; // select...where a = null and b < 5 (max-before)
// select...where a='a' and b is null and c !='a' (max-after)
else
boundsPtr->LoBound.Infinity[0] = QMY_NEG_INFINITY; // select...where x < y
}
} // end min_key is null
}
else // min_key is not null
{
if (literalCnt) litDefPtr = litDefPtr + 1;
literalCnt = literalCnt + 1;
boundsPtr->LoBound.Position = literalCnt;
/*
Determine inclusion or exclusion.
*/
if (min_key->flag == HA_READ_KEY_EXACT || //select...where a like 'this%'
/* An example for the following conditions is 'select...where a = 5 and b > null'. */
(max_key &&
(memcmp((uchar*)minPtr,(uchar*)maxPtr,
curKey.key_part[partsInUse].store_length)==0)))
{
if ((min_key->flag != HA_READ_KEY_EXACT) ||
(max_key &&
(memcmp((uchar*)minPtr,(uchar*)maxPtr,
curKey.key_part[partsInUse].store_length)==0)))
overrideInclusion = true; // Need inclusion for both min and max
}
else
boundsPtr->LoBound.Embodiment[0] = QMY_EXCLUSION;
litDefPtr->FieldNbr = field->field_index + 1;
DB2Field& db2Field = db2Table->db2Field(field->field_index);
litDefPtr->DataType = db2Field.getType();
/*
Convert the literal to DB2 format
*/
if ((field->type() != MYSQL_TYPE_BIT) && // Don't do conversion on BIT data
(field->charset() != &my_charset_bin) && // Don't do conversion on BINARY data
(litDefPtr->DataType == QMY_CHAR ||
litDefPtr->DataType == QMY_VARCHAR ||
litDefPtr->DataType == QMY_GRAPHIC ||
litDefPtr->DataType == QMY_VARGRAPHIC))
{
// Most of the code is required by the considerable wrangling needed
// to prepare partial keys for use by DB2
// 1. UTF8 (CCSID 1208) data can be copied across unmodified if it is
// utf8_bin. Otherwise, we need to convert the min and max
// characters into the min and max characters employed
// by the DB2 sort sequence. This is complicated by the fact that
// the character widths are not always equal.
// 2. Likewise, UCS2 (CCSID 13488) data can be copied across unmodified
// if it is ucs2_bin or ucs2_general_ci. Otherwise, we need to
// convert the min and max characters into the min and max characters
// employed by the DB2 sort sequence.
// 3. All other data will use standard iconv conversions. If an
// unconvertible character is encountered, we assume it is the min
// char and fill the remainder of the DB2 key with 0s. This may not
// always be accurate, but it is probably sufficient for range
// estimations.
const char* keyData = minPtr+((curKey.key_part[partsInUse].null_bit)? 1 : 0);
char* db2Data = literalPtr;
uint16 outLen = db2Field.getByteLengthInRecord();
uint16 inLen;
if (litDefPtr->DataType == QMY_VARCHAR ||
litDefPtr->DataType == QMY_VARGRAPHIC)
{
inLen = *(uint8*)keyData + ((*(uint8*)(keyData+1)) << 8);
keyData += 2;
outLen -= sizeof(uint16);
db2Data += sizeof(uint16);
}
else
{
inLen = field->max_display_length();
}
size_t convertedBytes = 0;
if (db2Field.getCCSID() == 1208)
{
DBUG_ASSERT(inLen <= outLen);
if (strcmp(field->charset()->name, "utf8_bin"))
{
const char* end = keyData+inLen;
const char* curKey = keyData;
char* curDB2 = db2Data;
uint32 min = field->charset()->min_sort_char;
while ((curKey < end) && (curDB2 < db2Data+outLen-3))
{
my_wc_t temp;
int len = field->charset()->cset->mb_wc(field->charset(),
&temp,
(const uchar*)curKey,
(const uchar*)end);
if (temp != min)
{
DBUG_ASSERT(len <= 3);
switch (len)
{
case 3: *(curDB2+2) = *(curKey+2);
case 2: *(curDB2+1) = *(curKey+1);
case 1: *(curDB2) = *(curKey);
}
curDB2 += len;
}
else
{
*(curDB2++) = 0xEF;
*(curDB2++) = 0xBF;
*(curDB2++) = 0xBF;
}
curKey += len;
}
convertedBytes = curDB2 - db2Data;
}
else
{
memcpy(db2Data, keyData, inLen);
convertedBytes = inLen;
}
rc = 0;
}
else if (db2Field.getCCSID() == 13488)
{
DBUG_ASSERT(inLen <= outLen);
if (strcmp(field->charset()->name, "ucs2_bin") &&
strcmp(field->charset()->name, "ucs2_general_ci"))
{
const char* end = keyData+inLen;
const uint16* curKey = (uint16*)keyData;
uint16* curDB2 = (uint16*)db2Data;
uint16 min = field->charset()->min_sort_char;
while (curKey < (uint16*)end)
{
if (*curKey != min)
*curDB2 = *curKey;
else
*curDB2 = 0xFFFF;
++curKey;
++curDB2;
}
}
else
{
memcpy(db2Data, keyData, inLen);
}
convertedBytes = inLen;
rc = 0;
}
else
{
rc = convertFieldChars(toDB2,
field->field_index,
keyData,
db2Data,
inLen,
outLen,
&convertedBytes,
true);
if (rc == DB2I_ERR_ILL_CHAR)
{
// If an illegal character is encountered, we fill the remainder
// of the key with 0x00. This was implemented as a corollary to
// Bug#45012, though it should probably remain even after that
// bug is fixed.
memset(db2Data+convertedBytes, 0x00, outLen-convertedBytes);
convertedBytes = outLen;
rc = 0;
}
}
if (!rc &&
(litDefPtr->DataType == QMY_VARGRAPHIC ||
litDefPtr->DataType == QMY_VARCHAR))
{
*(uint16*)(db2Data-sizeof(uint16)) =
convertedBytes / (litDefPtr->DataType == QMY_VARGRAPHIC ? 2 : 1);
}
}
else // Non-character fields
{
rc = convertMySQLtoDB2(field,
db2Field,
literalPtr,
(uchar*)minPtr+((curKey.key_part[partsInUse].null_bit)? 1 : 0));
}
if (rc != 0) break;
litDefPtr->Offset = (uint32_t)(literalPtr - literalsPtr);
litDefPtr->Length = db2Field.getByteLengthInRecord();
literalPtr = literalPtr + litDefPtr->Length; // Bump pointer for next literal
}
/* If there is a max_key value for this field, and if the max_key value is
the same as the min_key value, then the low bound literal can be reused
for the high bound literal. This eliminates the overhead of copying and
converting the same value twice. */
if (max_key && ((partsInUse + 1) <= maxKeyCnt) &&
(memcmp((uchar*)minPtr,(uchar*)maxPtr,
curKey.key_part[partsInUse].store_length)==0 || endOfLiteralPtr))
reuseLiteral = true;
minPtr += curKey.key_part[partsInUse].store_length;
}
/*
Build the high bound for the key range.
*/
if (max_key == NULL || ((partsInUse + 1) > maxKeyCnt))
boundsPtr->HiBound.Infinity[0] = QMY_POS_INFINITY;
else
{
if ((curKey.key_part[partsInUse].null_bit) && maxPtr[0])
{
if (min_key == NULL)
boundsPtr->HiBound.Infinity[0] = QMY_POS_INFINITY;
else
boundsPtr->HiBound.IsNull[0] = QMY_YES; // select...where x is null
}
else // max_key field is not null
{
if (boundsPtr->LoBound.IsNull[0] == QMY_YES) // select where x < 10 or x is null
{
rc = (int) HA_POS_ERROR;
break;
}
if (!reuseLiteral)
{
if (literalCnt)
litDefPtr = litDefPtr + 1;
literalCnt = literalCnt + 1;
litDefPtr->FieldNbr = field->field_index + 1;
DB2Field& db2Field = db2Table->db2Field(field->field_index);
litDefPtr->DataType = db2Field.getType();
/*
Convert the literal to DB2 format
*/
if ((field->type() != MYSQL_TYPE_BIT) && // Don't do conversion on BIT data
(field->charset() != &my_charset_bin) && // Don't do conversion on BINARY data
(litDefPtr->DataType == QMY_CHAR ||
litDefPtr->DataType == QMY_VARCHAR ||
litDefPtr->DataType == QMY_GRAPHIC ||
litDefPtr->DataType == QMY_VARGRAPHIC))
{
// We need to handle char fields in a special way in order to account
// for partial keys. Refer to the note above for a description of the
// basic design.
char* keyData = maxPtr+((curKey.key_part[partsInUse].null_bit)? 1 : 0);
char* db2Data = literalPtr;
uint16 outLen = db2Field.getByteLengthInRecord();
uint16 inLen;
if (litDefPtr->DataType == QMY_VARCHAR ||
litDefPtr->DataType == QMY_VARGRAPHIC)
{
inLen = *(uint8*)keyData + ((*(uint8*)(keyData+1)) << 8);
keyData += 2;
outLen -= sizeof(uint16);
db2Data += sizeof(uint16);
}
else
{
inLen = field->max_display_length();
}
size_t convertedBytes;
if (db2Field.getCCSID() == 1208)
{
if (strcmp(field->charset()->name, "utf8_bin"))
{
const char* end = keyData+inLen;
const char* curKey = keyData;
char* curDB2 = db2Data;
uint32 max = field->charset()->max_sort_char;
while (curKey < end && (curDB2 < db2Data+outLen-3))
{
my_wc_t temp;
int len = field->charset()->cset->mb_wc(field->charset(), &temp, (const uchar*)curKey, (const uchar*)end);
if (temp != max)
{
DBUG_ASSERT(len <= 3);
switch (len)
{
case 3: *(curDB2+2) = *(curKey+2);
case 2: *(curDB2+1) = *(curKey+1);
case 1: *(curDB2) = *(curKey);
}
curDB2 += len;
}
else
{
*(curDB2++) = 0xE4;
*(curDB2++) = 0xB6;
*(curDB2++) = 0xBF;
}
curKey += len;
}
convertedBytes = curDB2 - db2Data;
}
else
{
DBUG_ASSERT(inLen <= outLen);
memcpy(db2Data, keyData, inLen);
convertedBytes = inLen;
}
rc = 0;
}
else if (db2Field.getCCSID() == 13488)
{
if (strcmp(field->charset()->name, "ucs2_bin") &&
strcmp(field->charset()->name, "ucs2_general_ci"))
{
char* end = keyData+inLen;
uint16* curKey = (uint16*)keyData;
uint16* curDB2 = (uint16*)db2Data;
uint16 max = field->charset()->max_sort_char;
while (curKey < (uint16*)end)
{
if (*curKey != max)
*curDB2 = *curKey;
else
*curDB2 = 0x4DBF;
++curKey;
++curDB2;
}
}
else
{
memcpy(db2Data, keyData, outLen);
}
rc = 0;
}
else
{
size_t substituteChars = 0;
rc = convertFieldChars(toDB2,
field->field_index,
keyData,
db2Data,
inLen,
outLen,
&convertedBytes,
true,
&substituteChars);
if (rc == DB2I_ERR_ILL_CHAR)
{
// If an illegal character is encountered, we fill the remainder
// of the key with 0xFF. This was implemented to work around
// Bug#45012, though it should probably remain even after that
// bug is fixed.
memset(db2Data+convertedBytes, 0xFF, outLen-convertedBytes);
rc = 0;
}
else if ((substituteChars &&
(litDefPtr->DataType == QMY_VARCHAR ||
litDefPtr->DataType == QMY_CHAR)) ||
strcmp(field->charset()->name, "cp1251_bulgarian_ci") == 0)
{
// When iconv translates the max_sort_char with a substitute
// character, we have no way to know whether this affects
// the sort order of the key. Therefore, to be safe, when
// we know that substitute characters have been used in a
// single-byte string, we traverse the translated key
// in reverse, replacing substitue characters with 0xFF, which
// always sorts with the greatest weight in DB2 sort sequences.
// cp1251_bulgarian_ci is also handled this way because the
// max_sort_char is a control character which does not sort
// equivalently in DB2.
DBUG_ASSERT(inLen == outLen);
char* tmpKey = keyData + inLen - 1;
char* tmpDB2 = db2Data + outLen - 1;
while (*tmpKey == field->charset()->max_sort_char &&
*tmpDB2 != 0xFF)
{
*tmpDB2 = 0xFF;
--tmpKey;
--tmpDB2;
}
}
}
if (!rc &&
(litDefPtr->DataType == QMY_VARGRAPHIC ||
litDefPtr->DataType == QMY_VARCHAR))
{
*(uint16*)(db2Data-sizeof(uint16)) =
outLen / (litDefPtr->DataType == QMY_VARGRAPHIC ? 2 : 1);
}
}
else
{
rc = convertMySQLtoDB2(field,
db2Field,
literalPtr,
(uchar*)maxPtr+((curKey.key_part[partsInUse].null_bit)? 1 : 0));
}
if (rc != 0) break;
litDefPtr->Offset = (uint32_t)(literalPtr - literalsPtr);
litDefPtr->Length = db2Field.getByteLengthInRecord();
literalPtr = literalPtr + litDefPtr->Length; // Bump pointer for next literal
}
boundsPtr->HiBound.Position = literalCnt;
if (max_key->flag == HA_READ_BEFORE_KEY && !overrideInclusion)
boundsPtr->HiBound.Embodiment[0] = QMY_EXCLUSION;
}
maxPtr += curKey.key_part[partsInUse].store_length;
}
/*
Bump to the next field in the key composite.
*/
if ((partsInUse+1) < (int) keyCnt)
boundsPtr = boundsPtr + 1;
}
/*
Call DB2 to estimate the number of rows in the key range.
*/
if (rc == 0)
{
rc = db2i_ileBridge::getBridgeForThread()->recordsInRange((indexHandles[inx] ? indexHandles[inx] : db2Table->indexFile(inx)->getMasterDefnHandle()),
spcPtr,
keyCnt,
literalCnt,
boundsOff,
litDefOff,
literalsOff,
cutoff,
(uint32_t)(literalPtr - (char*)spcPtr),
endByte,
&recCnt,
&rtnCode);
}
/*
Set the row count and return.
Beware that if this method returns a zero row count, MySQL assumes the
result set for the query is zero; never return a zero row count.
*/
if ((rc == 0) && (rtnCode == QMY_SUCCESS || rtnCode == QMY_EARLY_EXIT))
{
rows = recCnt ? (ha_rows)recCnt : 1;
}
rows = (rows > 0 ? rows : HA_POS_ERROR);
setIndexReadEstimate(inx, rows);
DBUG_PRINT("ha_ibmdb2i::recordsInRange",("Estimate %d rows for key %d", uint32(rows), inx));
DBUG_RETURN(rows);
}